Aerobic exercise

Aerobic exercise (also known as cardio) is physical exercise of low to high intensity that depends primarily on the aerobic energy-generating process.[1] "Aerobic" means "relating to, involving, or requiring free oxygen",[2] and refers to the use of oxygen to adequately meet energy demands during exercise via aerobic metabolism.[3] Generally, light-to-moderate intensity activities that are sufficiently supported by aerobic metabolism can be performed for extended periods of time.[1] What is generally called aerobic exercise might be better termed "solely aerobic", because it is designed to be low-intensity enough so that all carbohydrates are aerobically turned into energy.

Physical therapist, Col. Pauline Potts and Dr. Kenneth Cooper, both of the United States Air Force, advocated the concept of aerobic exercise. In the 1960s, Cooper started research into preventive medicine. He conducted the first extensive research on aerobic exercise on over 5,000 U.S. Air Force personnel[13][14] after becoming intrigued by the belief that exercise can preserve one's health. Cooper published his ideas in a 1968 book titled, "Aerobics". In 1970, he created his own institute (the Cooper Institute) for non-profit research and education devoted to preventive medicine and published a mass-market version of his book "The New Aerobics" in 1979. Cooper encouraged millions into becoming active and is now known as the "father of aerobics".[15][16]Aerobics developed as an exercise form in the 1970s and became popular worldwide in the 1980s after the release of Jane Fonda's exercise videos in 1982.[17][18]

Aerobic exercise comprises innumerable forms. In general, it is performed at a moderate level of intensity over a relatively long period of time. For example, running a long distance at a moderate pace is an aerobic exercise, but sprinting is not. Playing singles tennis, with near-continuous motion, is generally considered aerobic activity, while golf or two person team tennis, with brief bursts of activity punctuated by more frequent breaks, may not be predominantly aerobic. Some sports are thus inherently "aerobic", while other aerobic exercises, such as fartlek training or aerobic dance classes, are designed specifically to improve aerobic capacity and fitness. It is most common for aerobic exercises to involve the leg muscles, primarily or exclusively. There are some exceptions. For example, rowing to distances of 2,000 meters or more is an aerobic sport that exercises several major muscle groups, including those of the legs, abdominals, chest, and arms.

Aerobic exercise and fitness can be contrasted with anaerobic exercise, of which strength training and short-distance running are the most salient examples. The two types of exercise differ by the duration and intensity of muscular contractions involved, as well as by how energy is generated within the muscle.

New research on the endocrine functions of contracting muscles has shown that both aerobic and anaerobic exercise promote the secretion of myokines, with attendant benefits including growth of new tissue, tissue repair, and various anti-inflammatory functions, which in turn reduce the risk of developing various inflammatory diseases. Myokine secretion in turn is dependent on the amount of muscle contracted, and the duration and intensity of contraction. As such, both types of exercise produce endocrine benefits.

In almost all conditions, anaerobic exercise is accompanied by aerobic exercises because the less efficient anaerobic metabolism must supplement the aerobic system due to energy demands that exceed the aerobic system's capacity. Common kettlebell exercises combine aerobic and anaerobic aspects.

Cooper himself defines aerobic exercise as the ability to use the maximum amount of oxygen during exhaustive work. Cooper describes some of the major health benefits of aerobic exercise, such as gaining more efficient lungs by maximizing breathing capacity, thereby increasing ability to ventilate more air in a shorter period of time. As breathing capacity increases, one is able to extract oxygen more quickly into the blood stream, increasing elimination of carbon dioxide. With aerobic exercise the heart becomes more efficient at functioning, and blood volume, hemoglobin and red blood cells increase, enhancing the ability of the body to transport oxygen from the lungs into the blood and muscles. Metabolism will change and enable consumption of more calories without putting on weight. Aerobic exercise can delay osteoporosis as there is an increase in muscle mass, a loss of fat and an increase in bone density. With these variables increasing, there is a decrease in likelihood of diabetes as muscles use sugars better than fat. One of the major benefits of aerobic exercise is that body weight may decrease slowly; it will only decrease at a rapid pace if there is a calorie restriction, therefore reducing obesity rates.[19]

Overuse injuries because of repetitive, high-impact exercise such as distance running

Is not an effective approach to building muscle

Not an effective form of fat loss, unless used consistently

Both the health benefits and the performance benefits, or "training effect", require that the duration and the frequency of exercise both exceed a certain minimum. Most authorities suggest at least twenty minutes performed at least three times per week.[23]

Higher intensity exercise, such as High-intensity interval training (HIIT), increases the resting metabolic rate (RMR) in the 24 hours following high intensity exercise,[24] ultimately burning more calories than lower intensity exercise; low intensity exercise burns more calories during the exercise, due to the increased duration, but fewer afterwards.